1. Field of the Invention
The present invention relates to golf balls. More particularly, the present invention relates to improvement of dimples of a golf ball.
2. Description of the Related Art
Golf balls have numerous dimples on the surface thereof. In general, golf balls have single radius dimples having a cross-sectional shape with single curvature radius, or double radius dimples having a cross-sectional shape with two curvature radii. A role of the dimples involves causing turbulent flow separation through disrupting the air flow around the golf ball during the flight. This role is referred to as a “dimple effect”. By causing the turbulent flow separation, a separating point of air from the golf ball shifts backwards leading to the reduction of a drag. The turbulent flow separation promotes the differential between the separating points at the upper and lower sides of the golf ball, which result from the backspin, thereby enhancing the lift force that acts upon the golf ball. Excellent dimples disturb the air flow more efficiently.
A variety of proposals with respect to the cross-sectional shape of the dimples in an attempt to improve flight performances have been made. U.S. Pat. No. 5,338,039 discloses dimples having a shape with the gradient of a slope disposed in the vicinity of the edge being greater than that of a slope at the bottom part. U.S. Pat. No. 5,735,757 discloses dimples having a cross-sectional shape given by double radius.
Top concern to golf players for golf balls is the travel distance. In light of elevation of the travel distance, there remains room for an improvement of the cross-sectional shape of the dimple. An object of the present invention is to provide a golf ball that has improved dimples, and is excellent in the flight performance.